Organometallic compound and organic light-emitting device including the same

ABSTRACT

An organometallic compound represented by Formula 1: 
       M(L 1 ) n1 (L 2 ) n2   Formula 1
 
     wherein, in Formula 1,
     L 1  is a ligand represented by Formula 2,   L 2  is a ligand represented by one of Formulae 3 to 5, and   n1 and n2 are each independently 1 or 2,
 
wherein Formulae 1 to 5 are described in the specification.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2014-0027947, filed on Mar. 10, 2014, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. §119, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

1. Field

The present inventive concept relates to organometallic compounds and organic light-emitting devices including the organometallic compounds

2. Description of the Related Art

Organic light-emitting devices (OLEDs) are self-emitting devices, which have advantages such as wide viewing angles, excellent contrast ratios, and quick response times. In addition, the OLEDs exhibit high brightness, excellent driving voltage characteristics, and can provide multicolored images.

A typical organic light-emitting device may include an anode, a cathode, and an organic layer, including an emission layer, disposed between the anode and the cathode. The organic light-emitting device may also include a hole transport region disposed between the anode and the emission layer, and an electron transport region disposed between the emission layer and the cathode. Holes injected from the anode move to the emission layer via the hole transport region, while electrons injected from the cathode move to the emission layer via the electron transport region. Carriers such as the holes and electrons recombine in an emission layer to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted.

Various types of organic light emitting devices are known. However, there still remains a need in OLEDs having low driving voltage, high efficiency, high brightness, and long lifespan.

SUMMARY

Provided are organometallic compounds and organic light-emitting devices including the organometallic compounds.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

According to an aspect of the present inventive concept, an organometallic compound represented by Formula 1 is provided:

M(L₁)_(n1)(L₂)_(n2)  Formula 1

wherein, in Formula 1,

L₁ is a ligand represented by Formula 2, and

L₂ is a ligand represented by one of Formulae 3 to 5:

wherein, in Formulae 1 to 5,

M is Ir, Pt, Os, Ti, Zr, Hf, Eu, Th, or Tm;

CY₁ and CY₂ are each independently a benzene, a naphthalene, a fluorene, a spiro-fluorene, an indene, a pyrrole, a thiophene, a furan, an imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isoxazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, an benzoxazole, an isobenzoxazole, a triazole, a tetrazole, an oxadiazole, a triazine, a dibenzofuran, or a dibenzothiophene, wherein CY₁ and CY₂ are optionally linked to each other via a single bond or a first linking group;

Y₁ to Y₄ are each independently C or N;

Y₁ and Y₂ are linked to each other via a single bond or a double bond, and

Y₃ and Y₄ are linked to each other via a single bond or a double bond;

X₁ is N or CR₁;

X₂ is N or CR₂;

X₃ is N or CR₃;

X₄ is N or CR₄;

X₁₁ is N or CR₁₁;

X₁₂ is N or CR₁₂;

X₁₃ is N or CR₁₃;

X₁₄ is N or CR₁₄;

X₁₅ is N or CR₁₅;

X₁₆ is N or CR₁₆;

Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₂-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, or —Si(Q₁)(Q₂)(Q₃), wherein R₂₁ and R₂₂ are optionally linked to each other via a single bond or a second linking group represented by Formula 7:

*—(Z₃₂)_(b2)-*′  Formula 7

Z₃₂ is *—O—*′, *—S—*′, *—N(Q₅₁)—*′, *—C(Q₅₂)(Q₅₃)—*′, *—C(Q₅₄)=C(Q₅₅)-*′, or

b2 is an integer selected from 1 to 10, and when b2 is 2 or greater, groups Z₃₂ are identical to or different from each other;

a1 and a2 are each independently an integer selected from 0 to 5;

n1 and n2 are each independently 1 or 2;

* and *′ each indicates a binding site to M in Formula 1;

when the ligand of Formula 2 is represented by Formula 2A, a2 in Formula 2A is 2, and Z₂ in Formula 2A is —F;

at least one of X₁₁ to X₁₆ in Formula 4 is N;

the following conditions regarding R₂₁ and R₂₂ in Formula 5 are excluded

i) where R₂₁ and R₂₂ are both phenyl groups,

ii) where R₂₁ and R₂₂ are both phenyl groups substituted with a tert-butyl group,

iii) where R₂₁ and R₂₂ are both ethyl groups,

iv) where R₂₁ and R₂₂ are both propyl groups,

v) where R₂₁ and R₂₂ are both butyl groups, and

vi) where R₂₁ and R₂₂ are both —Si(CH₃)₃;

-   -   at least one substituent of the substituted C₁-C₆₀ alkyl group,         the substituted C₂-C₆₀ alkenyl group, the substituted         C₂-C_(α)alkynyl group, the substituted C₁-C₆₀ alkoxy group, the         substituted C₃-C₁₀ cycloalkyl group, the substituted C₂-C₁₀         heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl         group, the substituted C₂-C₁₀ heterocycloalkenyl group, the         substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy         group, the substituted C₆-C₆₀ arylthio group, the substituted         C₂-C₆₀ heteroaryl group, the substituted monovalent non-aromatic         condensed polycyclic group, and the substituted monovalent         non-aromatic condensed heteropolycydic group is

a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group,

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₁₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycydic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), and —B(Q₁₆)(Q₁₇),

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group,

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycydic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), and —B(Q₂₆)(Q₂₇), or

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), or —B(Q₃₆)(Q₃₇); wherein

Q₁ to Q₃, Q₁₁ to Q₁₇, Q₂₁ to Q₂₇, and Q₃₁ to Q₃₇ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group:

According to another aspect of the present inventive concept, an organic light-emitting device comprising: a first electrode; a second electrode; and an organic layer disposed between the first electrode and the second electrode and comprising an emission layer and at least one of the organometallic compounds.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic cross-sectional view of an organic light-emitting device according to an embodiment of the present disclosure; and

FIGS. 2 to 14 are graphs of emission intensity (arbitrary unit, a. u.) versus wavelength (nanometer, nm) illustrating photoluminescent (PL) spectra of Compounds 52, 19, 2, 50, 1, 3, 5, 9, 54, 53, 51, 56, and 30, respectively.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

It will be understood that when an element is referred to as being “on” another element, it can be directly in contact with the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The term “or” means “and/or.” It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this general inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.

According to an embodiment of the present inventive concept, there is provided an organometallic compound represented by Formula 1:

M(L₁)_(n1)(L₂)_(n2)  Formula 1

In Formula 1, L₁ may be a ligand represented by Formula 2, and L₂ may be a ligand represented by one of Formulae 3 to 5:

In Formulae 2 to 5, * and *′ each indicates a binding site to M in Formula 1. Thus, the organometallic compound of Formula 1 may be represented by Formula 1A, 1B, or 1C:

In Formulae 1A to 1C, M, CY₁, CY₂, Y₁ to Y₄, X₁ to X₄, X₁₁ to X₁₆, Z₁ to Z₄, R₂₁, R₂₂, n1, and n2 are the same as those defined herein.

In Formula 1, M may be iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), or thulium (Tm). For example, M in Formula 1 may be Ir or Pt.

In Formula 2, CY₁ and CY₂ may be each independently a benzene, a naphthalene, a fluorene, a spiro-fluorene, an indene, a pyrrole, a thiophene, a furan, an imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isoxazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, a benzoxazole, an isobenzoxazole, a triazole, a tetrazole, an oxadiazole, a triazine, a dibenzofuran, or a dibenzothiophene, wherein CY₁ and CY₂ may be optionally linked to each other via a single bond or a first linking group.

The first linking group may be represented by Formula 6:

*—(Z₃₁)_(b1)—*′  Formula 6

In Formula 6, Z₃₁ may be *—O—*′, *—S—*′, *—N(Q₄₁)-*′, *—C(Q₄₂)(Q₄₃)-*′, *—C(Q₄₄)=C(Q₄₅)—*′, or

wherein Q₄₁ to Q₄₉ may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group,

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group,

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group, or

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocydoalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycydic group; and

b1 in Formula 6 may be an integer selected from 1 to 10, and when b1 is 2 or greater, groups Z₃₁ may be identical to or different from each other.

For example, in Formula 6, Q₄₁ to Q₄₉ may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinyl group, or

a phenyl group, a naphthyl group, a pyridinyl group, or a pyrimidinyl group. However, embodiments of the present inventive concept are not limited thereto.

For example, in Formula 2, CY₁ and CY₂ may be linked to each other via a single bond or a first linking group, and the first linking group may be represented by *—C(Q₄₄)=C(Q₄₅)-*′ or

(where b1 in Formula 6 is 1), wherein Q₄₄ to Q₄₉ may be each independently a hydrogen, a C₁-C₁₀ alkyl group, or a C₁-C₁₀ alkoxy group. However, embodiments of the present inventive concept are not limited thereto.

In some embodiments, in Formula 2, CY₁ and CY₂ may be each independently a benzene, a naphthalene, a fluorene, a thiophene, a furan, an imidazole, a pyrazole, a pyridine, a pyrimidine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, a triazole, a tetrazole, a triazine, a dibenzofuran, or a dibenzothiophene.

In some embodiments, CY₁ may be a pyridine or an imidazole, and CY₂ may be a benzene, a pyridine, or a dibenzofuran.

In Formula 2, Y₁ to Y₄ may be each independently a carbon (C) or a nitrogen (N). In Formula 2, Y₁ and Y₂ may be linked to each other via a single bond or a double bond, and Y₃ and Y₄ may be linked to each other via a single bond or a double bond.

For example, in Formula 2, Y₁ may be N, and Y₂ to Y₄ may be C. In some other embodiments, in Formula 2, Y₁, Y₃, and Y₄ may be C, and Y₂ may be N.

In some embodiments, when the ligand of Formula 2 is represented by Formula 2A, a2 in Formula 2A is 2, and Z₂ is —F:

In some embodiments, L₁ in Formula 1 may be selected from groups represented by Formulae 2-1 to 2-90:

In Formulae 2-1 to 2-90,

Z₁ and Z₂ may be the same as those defined above;

Z_(1a) and Z_(1b) are the same or different and may each have the same definition as Z₁;

Z_(2a), Z_(2b) and Z_(2c) are the same or different and may each have the same definition as Z₂;

a12 may be 1 or 2;

a13 may be an integer selected from 1 to 3;

a14 may be an integer selected from 1 to 4; and

* and *′ each indicates a binding site to M.

For example, in Formulae 2-1 to 2-90, Z₁, Z₂, Z_(1a), Z_(1b), Z_(2a), Z_(2b), and Z_(2c) may be each independently

a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, n-propyl group, an isopropyl group, n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or

a methyl group, an ethyl group, a n-propyl group, an isopropyl group, n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group. However, embodiments of the present inventive concept are not limited thereto.

In some other embodiments, L₁ in Formula 1 may be selected from groups represented by Formulae 2-1A, 2-2a, 2-70A, and 2-87A:

In Formulae 2-1A, 2-2A, 2-70A, and 2-87A,

Z₁ and Z₂ may be the same as those defined above,

Z_(2a), Z_(2b), and Z_(2c) are the same or different and may each have the same definition as Z₂, and

* and *′ each indicates a binding site to M.

In Formulae 4 and 5,

X₁ may be N or CR₁;

X₂ may be N or CR₂;

X₃ may be N or CR₃;

X₄ may be N or CR₄;

X₁₁ may be N or CR₁₁;

X₁₂ may be N or CR₁₂;

X₁₃ may be N or CR₁₃;

X₁₄ may be N or CR₁₄;

X₁₅ may be N or CR₁₅;

X₁₆ may be N or CR₁₆; and

at least one of X₁₁ to X₁₆ in Formula 5 may be N.

In some embodiments, at least one of X₁ to X₄ in Formula 3 may be N.

In some embodiments, Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ in above Formulae may be each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₂-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, or —Si(Q₁)(Q₂)(Q₃); and

R₂₁ and R₂₂ may be optionally linked to each other via a single bond or a second linking group represented by Formula 7:

*—(Z₃₂)_(b2)—*′  Formula 7

In Formula 7, Z₃₂ is *—O—*′, *—S—*′, *—N(Q₅₁)—*′, *—C(Q₅₂)(Q₅₃)-*′, —C(Q₅₄)=C(Q₅₅)-*′, or

b2 is an integer selected from 1 to 10, and when b2 is 2 or greater, groups Z₃₂ are identical to or different from each other;

In Formula 5, the following conditions regarding R₂₁ and R₂₂ are excluded:

-   -   i) where R₂₁ and R₂₂ are both phenyl groups,     -   ii) where R₂₁ and R₂₂ are both phenyl groups substituted with a         tert-butyl group,     -   iii) where R₂₁ and R₂₂ are both ethyl groups,     -   iv) where R₂₁ and R₂₂ are both propyl groups,     -   v) where R₂₁ and R₂₂ are both butyl groups, and     -   vi) where R₂₁ and R₂₂ are both —Si(CH₃)3.

In some other embodiments, Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ in above Formulae may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinyl group,

a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, a ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, a oxazolyl group, an isooxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzooxazolyl group, an isobenzooxazolyl group, a triazolyl group, a tetrazolyl group, a oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group,

a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or

—Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ may be each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, a fluorenyl group, a chrysenyl group, a carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinazolinyl group, or a quinoxalinyl group.

In some other embodiments, Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or

—Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ may be each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or a triazinyl group.

In some other embodiments, Z₁ to Z₄, R₁ to R₄, R₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ may be each independently

a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, n-propyl group, an isopropyl group, n-butyl group, an isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, tert-pentyl group, n-hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, n-heptyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, n-octyl group, isooctyl group, sec-octyl group, tert-octyl group, n-nonyl group, isononyl group, sec-nonyl group, tert-nonyl group, n-decyl group, isodecyl group, sec-decyl group, tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group;

a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group, or

—Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ may be each independently a hydrogen, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or a triazinyl group.

In some embodiments, L₂ in Formula 1 may be a group represented by one of Formulae 3-1 to 3-4 and Formulae 4-1 to 4-4:

In Formulae 3-1 to 3-4, and Formulae 4-1 to 4-4, Z₃, Z₄, R₁ to R₄, and R₁₁ to R₁₆ may be each independently the same as those defined above.

For example, in Formulae 3-1 to 3-4 and Formulae 4-1 to 4-4, Z₃, Z₄, R₁ to R₄, and R₁₁ to R₁₆ may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, or

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; and

* and *′ each indicates a binding site to M in Formula 1.

In some other embodiments, in Formulae 3-1 to 3-4 and Formulae 4-1 to 4-4, Z₃, Z₄, R₁ to R₄, and R₁₁ to R₁₆ may be each independently

-   -   a hydrogen, —F, a cyano group, a nitro group, a methyl group, an         ethyl group, n-propyl group, an isopropyl group, a n-butyl         group, an isobutyl group, a sec-butyl group, a tert-butyl group,         a n-pentyl group, an isopentyl group, a sec-pentyl group, a         tert-pentyl group, a n-hexyl group, an isohexyl group, a         sec-hexyl group, a tert-hexyl group, a n-heptyl group, an         isoheptyl group, a sec-heptyl group, a tert-heptyl group, a         n-octyl group, an isooctyl group, a sec-octyl group, a         tert-octyl group, a n-nonyl group, an isononyl group, a         sec-nonyl group, a tert-nonyl group, a n-decyl group, an         isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy         group, an ethoxy group, a propoxy group, a butoxy group, a         pentoxy group, a phenyl group, or a naphthyl group, or

a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group. However, embodiments of the present inventive concept are not limited thereto.

In some embodiments, R₂₁ and R₂₂ in Formula 5 may be each independently a cyano group or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or

—Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ may be each independently a hydrogen, a phenyl group, or a naphthyl group; and

at least one of R₂₁ and R₂₂ in Formula 5 may be

a cyano group or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, or

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group.

In some other embodiments, R₂₁ and R₂₂ in Formula 5 may be each independently

a cyano group or a C₁-C₂₀ alkoxy group,

a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group,

a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, or

—Si(Q₁X)(Q₂)(Q₃), wherein Q₁ to Q₃ are each independently a hydrogen, a phenyl group, or a naphthyl group; and

at least one of R₂₁ and R₂₂ in Formula 5 may be

a cyano group or a C₁-C₂₀ alkoxy group,

a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, or

a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group. However, embodiments of the present inventive concept are not limited thereto.

In some embodiments, L₂ in Formula 1 is a group represented by Formula 5A or 5B:

In Formulae 5A and 5B,

Z₃, Z₄, Z₃₂, and b2 may be the same as those defined in claim 1;

X₃₁ may be N or CR₃₁;

X₃₂ may be N or CR₃₂;

X₃₃ may be N or CR₃₃;

X₃₄ may be N or CR₃₄;

X₃₅ may be N or CR₃₅;

X₃₆ may be N or CR₃₆;

X₃₇ may be N or CR₃₇;

X₃₈ may be N or CR₃₈;

at least one of X₃₁ to X₃₈ may be N; and

R₃₁ to R₃₈ are the same or different and may each have the same definition as R₁.

For example, R₃₁ to R₃₈ in Formulae 5A and 5B may be each independently

a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or

a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group. However, embodiments of the present inventive concept are not limited thereto.

In some embodiments, L₂ in Formula 1 may be selected from groups represented by Formulae 5-1 to 5-25. However, embodiments of the present inventive concept are not limited thereto.

In Formulae 5-1 to 5-25, Z₃, Z₄, R₃₁ to R₃₈, and Q₅₂ to Q₅₅ may be the same as those defined above.

For example, in Formulae 5-1 to 5-25, Z₃, Z₄, R₃₁ to R₃₈, and Q₅₂ to Q₅₅ may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, or

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group;

d1 may be an integer selected from 1 to 4;

d2 may be an integer selected from 1 to 5;

d3 may be an integer selected from 1 to 3;

d4 may be 1 or 2; and

d5 may be an integer selected from 1 to 7.

In some other embodiments, in Formulae 5-1 to 5-25, Z₃, Z₄, R₃₁ to R₃₈, and Q₅₂ to Q₅₅ may be each independently

a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or

a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group. However, embodiments of the present inventive concept are not limited thereto.

In some embodiments, in Formula 2,

CY₁ may be a pyridine or an imidazole;

CY₂ may be a benzene, a pyridine, or a dibenzofuran;

Z₁ and Z₂ may be each independently

a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or

a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of-F, a cyano group, and a nitro group; and

L₂ in Formula 1 may be a ligand represented by one of Formulae 3-1 to 3-4, Formulae 4-1 to 4-4, and Formulae 5-1 to 5-25.

In some embodiments,

L₁ in Formula 1 may be a ligand represented by one of Formulae 2-1 to 2-90, and L₂ in Formula 1 may be a ligand represented by one of Formulae 3-1 to 3-4, Formulae 4-1 to 4-4, and Formulae 5-1 to 5-25.

In some other embodiments, L₁ in Formula 1 may be a ligand represented by one of Formulae 2-1A, 2-2A, 2-70A, and 2-87A, and L₂ in Formula 1 may be a ligand represented by one of Formulae 3-1 to 3-4, Formulae 4-1 to 4-4, and Formulae 5-1 to 5-25.

In Formula 2, a1 and a2, which indicate the number of groups Z₁ and the number of groups Z₂, respectively, may be each independently an integer of 0 to 5. For example, a1 may be 0, 1, or 2, and a2 may be 0, 1, 2, or 3.

When a1 is 2 or greater, a1 number of groups Z₁ may be identical to or different from each other. When a2 is 2 or greater, a2 number of groups Z₂ may be identical to or different from each other.

In Formula 1, n1 and n2 may be each independently 1 or 2.

For example, in Formula 1, M may be Ir; n1 may be 1; and n2 may be 2. In some other embodiments, n1 may be 2, and n2 may be 1.

In some embodiments, the organometallic compound of Formula 1 may be one of Compounds 1 to 56:

In Formula 1, L₁ may be a ligand represented by Formula 2 as described above. Thus, an organic light-emitting device including the organometallic compound of Formula 1 may have an improved emission efficiency.

In Formula 1, L₂ may be one of the ligands represented by Formulae 3 to 5 as described above,

As described above, X₁ to X₄ in Formula 3 may be each independently nitrogen (N), and at least one of X₁₁ to X₁₆ in Formula 4 may be N. Thus, an organometalic compound including a ligand represened by Formula 3 and 4 may have improved electron mobility and improved electron transport ability. Thus, an organic light-emitting device including the organometallic compound of Formula 1, wherein L₂ is a ligand represented by Formula 3 or 4, may have an improved emission efficiency.

In Formula 5, the following conditions regarding R₂₁ and R₂₂ are excluded:

i) where R₂₁ and R₂₂ are both phenyl groups, ii) where R₂₁ and R₂₂ are both phenyl groups substituted with a tert-butyl group, iii) where R₂₁ and R₂₂ are both ethyl groups, iv) where R₂₁ and R₂₂ are both propyl groups, v) where R₂₁ and R₂₂ are both butyl groups, and vi) where R₂₁ and R₂₂ are both —Si(CH₃)₃. For example, at least one of R₂₁ and R₂₂ in Formula 5 may be

a cyano group or a C₁-C₂₀ alkoxy group,

a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group,

a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or

—Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ may be each independently selected from a hydrogen, a phenyl group, and a naphthyl group.

An organometallic compound including the ligand of Formula 5 may have improved electron mobility and improved electron transport ability. Thus, an organic light-emitting device including the organometallic compound of Formula 1, wherein L₂ is a ligand of Formula 5, may have improved emission efficiency.

For example, the organometallic compound of Formula 1 may emit deep blue light having a peak emission wavelength of about 435 nanometers (nm) to about 500 nm, an x-color coordinate of about 0.14 to about 0.25, for example, about 0.16 to about 0.23, and a y-color coordinate of about 0.10 to about 0.41, for example, about 0.25 to about 0.35.

A synthesis method of the organometallic compound of Formula 1 above may be easily understood to one of ordinary skill in the art based on the synthesis examples described below.

As described above, the organometallic compound of Formula 1 above may be appropriate for use as a material for the organic layer, for example, a dopant of the EML.

According to another embodiment of the present disclosure, an organic light-emitting device includes

a first electrode,

a second electrode, and

an organic layer disposed between the first electrode and the second electrode,

wherein the organic layer includes an EML and at least one of the organometallic compounds of Formula 1 above.

Due to the inclusion of the organic layer including the organometallic compound of Formula 1 described above, the organic light-emitting device may have a low driving voltage, a high efficiency, and a long lifetime.

The organometallic compound of Formula 1 above may be used between a pair of electrodes of an organic light-emitting device. For example, the organometallic compound of Formula 1 may be included in the EML. In this regard, the organometallic compound of Formula 1 may serve as a dopant in the EML, and the EML may further include a host. The EML may emit red light, green light, or blue light.

As used herein, the phrase “(for example, the organic layer) including at least one organometallic compound means that “(the organic layer) including one of the organometallic compounds of Formula 1 above, or at least two different organometallic compounds of Formula 1 above”.

For example, the organic layer of the organic light-emitting device may include only Compound 1 as the organometallic compound. For example, Compound 1 may be included in the EML of the organic light-emitting device. In some embodiments, the organic layer of the organic light-emitting device may include Compounds 1 and 2 as the organometallic compound. For example, Compounds 1 and 2 may be included both in the EML.

The first electrode may be an anode as a hole injection electrode, and the second electrode may be a cathode as an electron injection electrode. In some embodiments, the first electrode may be a cathode as an electron injection electrode, and the second electrode may be an anode as a hole injection electrode.

For example, the first electrode may be an anode, the second electrode may be a cathode, and the organic layer may include:

i) a hole transport region disposed between the first electrode and the emission layer and including at least one of a hole injection layer, a hole transport layer, and an electron blocking layer; and

ii) an electron transport region disposed between the emission layer and the second electrode and including at least one of a hole blocking layer, an electron transport layer, and an electron injection layer.

The term “organic layer” as used herein refers to a single layer and/or a plurality of layers disposed between the first and second electrodes of the organic light-emitting device. The “organic layer” may include, for example, an organic compound or an organometallic complex including a metal.

FIG. 1 is a schematic view of an organic light-emitting device 10 according to an embodiment of the present disclosure. Hereinafter, a structure of an organic light-emitting device according to an embodiment of the present disclosure and a method of manufacturing the same will now be described with reference to FIG. 1. Referring to FIG. 1, the organic light-emitting device 10 has a structure in which a substrate 11, a first electrode 11, an organic layer 15, and a second electrode 19 are sequentially stacked in this order.

A substrate (not shown) may be disposed under the first electrode 11 or on the second electrode 190 in FIG. 1. The substrate may be any substrate that is used in conventional organic light emitting devices. In some embodiments the substrate may be a glass substrate or a transparent plastic substrate with strong mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance.

The first electrode 11 may be formed by depositing or sputtering a first electrode-forming material on the substrate 11. The first electrode 11 may be an anode. A material having a high work function may be selected as a material for the first electrode to facilitate hole injection. The first electrode 11 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. For example, the material for the first electrode 13 may be indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), or zinc oxide (ZnO). In some embodiments, the material for the first electrode 13 may be metals, for example, magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), or the like.

The first electrode 11 may have a single-layer structure or a multi-layer structure including at least two layers. For example, the first electrode 11 may have, but not limited to, a three-layered structure including ITO, Ag, and ITO layers.

The organic layer 15 may be disposed on the first electrode 11.

The organic layer 15 may include at least one a hole transport region; an EML, and an electron transport region.

The hole transport region may be disposed between the first electrode 11 and the EML.

The hole transport region may include at least one of a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), and a buffer layer.

The hole transport region may include exclusively the HIL or the HTL. In some embodiments, the electron transport region may have a structure including a HIL/HTL or a HIL/HTL/EBL, wherein the layers forming the structure of the electron transport region may be sequentially stacked on the first electrode 10 in the stated order.

When the hole transport region includes the HIL, the HIL may be formed on the first electrode 11 by any of a variety of methods, for example, vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) deposition, or the like.

When the HIL is formed using vacuum deposition, vacuum deposition conditions may vary depending on the material that is used to form the HIL, and the desired structure and thermal properties of the HIL to be formed. For example, vacuum deposition may be performed at a temperature of about 100° C. to about 500° C., a pressure of about 10⁻⁸ torr to about 10⁻³ torr, and a deposition rate of about 0.01 to about 100 Angstroms per second (Å/sec). However, the deposition conditions are not limited thereto.

When the HIL is formed using spin coating, the coating conditions may vary depending on the material that is used to form the HIL, and the desired structure and thermal properties of the HIL to be formed. For example, the coating rate may be in the range of about 2,000 revolutions per minute (rpm) to about 5,000 rpm, and a temperature at which heat treatment is performed to remove a solvent after coating may be in a range of about 80° to about 200° C. However, the coating conditions are not limited thereto.

Conditions for forming the HTL and the EBL may be the same as those for the HIL described above.

In some embodiments, the hole transport region may include at least one of m-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, Spiro-TPD, Spiro-NPB, methylated-NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzene sulfonic acid (Pani/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate)(PEDOT/PSS), polyaniline/camphor sulfonic acid (Pani/CSA), polyaniline/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201 below, and a compound represented by Formula 202 below.

In Formula 201 above, Ar₁₀₁ and Ar₁₀₂ may be each independently

a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an acenaphthylene group, a fluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, or a pentacenylene group, or

a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an acenaphthylene group, a fluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, or a pentacenylene group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocydoalkyl group, a C₂-C₁₀ heterocydoalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycydic group, and a monovalent non-aromatic condensed heteropolycyclic group.

In Formula 201, xa and xb may be each independently an integer from 0 to 5, for example, may be 0, 1, or 2. For example, xa may be 1, and xb may be 0, but are not limited thereto.

In Formulae 201 and 202, R₁₀₁ to R₁₀₈, R₁₁₁ to R₁₁₉, and R₁₂₁ to R₁₂₄ may be each independently

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or the like), or a C₁-C₁₀ alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, or the like),

a C₁-C₁₀ alkyl group or a C₁-C₁₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof,

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, or a pyrenyl group, or

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, or a pyrenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, and a C₁-C₁₀ alkoxy group. However, embodiments of the present disclosure are not limited thereto.

In Formula 201 above, R₁₀₉ may be

a phenyl group, a naphthyl group, an anthracenyl group, or a pyridinyl group, or

a phenyl group, a naphthyl group, an anthracenyl group, or a pyridinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, and a pyridinyl group.

In some embodiments, the compound of Formula 201 may be a compound represented by Formula 201A, but is not limited thereto:

In Formula 201A, R₁₀₁, R₁₁₁, R₁₁₂, and R₁₀₉ may be the same as those defined above.

For example, the compound of Formula 201 and the compound of Formula 202 may be Compounds HT1 to HT20 below, but are not limited thereto:

A thickness of the hole transport region may be from about 100 Å to about 10,000 Å, and in some embodiments, from about 100 Å to about 1,000 Å. When the hole transport region includes a HIL and a HTL, a thickness of the HIL may be from about 100 Å to about 10,000 Å, and in some embodiments, from about 100 Å to about 1,000 Å, and a thickness of the HTL may be from about 50 Å to about 2,000 Å, and in some embodiments, from about 100 Å to about 1,500 Å. When the thicknesses of the hole transport region, the HIL, and the HTL are within these ranges, satisfactory hole transport characteristics may be obtained without a substantial increase in driving voltage.

The hole transport region may further include a charge-generating material to improve conductivity, in addition to the materials as described above. The charge-generating material may be homogeneously or non-homogeneously dispersed in the hole transport region.

The charge-generating material may be, for example, a p-dopant. The p-dopant may be one of a quinine derivative, a metal oxide, and a cyano group-containing compound, but is not limited thereto. Non-limiting examples of the p-dopant are quinone derivatives such as tetracyanoquinonedimethane (TCNQ), 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ), and the like; metal oxides such as tungsten oxide, molybdenum oxide, and the like; and cyano-containing compounds such as Compound 200 below.

The hole transport region may further include a buffer layer.

The buffer layer may compensate for an optical resonance distance of light according to a wavelength of the light emitted from the EML, and thus may increase efficiency.

The EML may be formed on the hole transport region by using vacuum deposition, spin coating, casting, LB deposition, or the like. When the EML is formed using vacuum deposition or spin coating, the conditions for deposition and coating may be similar to those for the formation of the HIL, though the conditions for the deposition and coating may vary depending on the material that is used to form the EML.

The EML may include a host and a dopant.

The host may include at least one of TPBi, TBADN, AND (also referred to as “DNA”), CBP, CDBP, and TCP:

In some embodiments, the host may further include a compound represented by Formula 301:

In Formula 301, Ar₁₁₁ and Ar₁₁₂ may be each independently

a phenylene group, a naphthylene group, a phenanthrenylene group, or a pyrenylene group, or

a phenylene group, a naphthylene group, a phenanthrenylene group, a fluorenyl group, or a pyrenylene group, each substituted with at least one of a phenyl group, a naphthyl group, and an anthracenyl group.

In Formula 301, Ar₁₁₃ to Ar₁₁₆ may be each independently

a C₁-C₁₀ alkyl group, a phenyl group, a naphthyl group, a phenanthrenyl group, or a pyrenyl group, or

a phenyl group, a naphthyl group, a phenanthrenyl group, a fluorenyl group, or a pyrenyl group, each substituted with at least one of a phenyl group, a naphthyl group, and an anthracenyl group.

In Formula 301, g, h, l, and j may be each independently an integer of 0 to 4, for example, 0, 1, or 2.

In Formula 301, Ar₁₁₃ to Ar₁₁₆ may be each independently

a C₁-C₁₀ alkyl group substituted with at least one of a phenyl group, a naphthyl group, and an anthracenyl group,

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, or a fluorenyl group,

a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, or a fluorenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, and a fluorenyl group, or

However, embodiments of the present inventive concept are not limited thereto.

In some embodiments, the host may include a compound represented by Formula 302:

In Formula 302, Ar₁₂₂to Ar₁₂₅ may be defined the same as for Ar₁₁₃ in Formula 301 described above.

In Formula 302, Ar₁₂₆ and Ar₁₂₇ may be each independently a C₁-C₁₀ alkyl group, for example, a methyl group, an ethyl group, or a propyl group.

In Formula 302, k and l may be each independently an integer of 0 to 4, for example, 0, 1, or 2.

Non-limiting examples of the compound of Formula 301 and the compound of Formula 302 may include Compounds H1 to H42. However, embodiments of the present inventive concept are not limited thereto.

When the organic light-emitting device is a full color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and a blue emission layer. In some embodiments, the EML may have a stack structure including a red emission layer, a green emission layer, and/or a blue emission layer that are stacked upon one another to emit white light, but is not limited thereto.

The EML may include the organometallic compound of Formula 1 as a dopant.

When the EML includes both a host and a dopant, the amount of the dopant may be from about 0.01 to about 20 parts by weight based on 100 parts by weight of the host. However, the amount of the dopant is not limited to this range.

The thickness of the EML may be about 100 Å to about 1,000 Å, and in some embodiments, may be from about 200 Å to about 600 Å. When the thickness of the EML is within these ranges, the EML may have improved light emitting ability without a substantial increase in driving voltage.

Next, the electron transport region may be formed on the EML.

The electron transport region may include at least one of a HBL, an ETL, and an EIL.

In some embodiments, the electron transport region may have a structure including a HBL/ETL/EIL, or an ETL/EIL, wherein the layers forming the structure of the electron transport region may be sequentially stacked on the EML in the stated order. However, embodiments of the present disclosure are not limited thereto. The ETL may have a single-layer structure or a multi-layer structure including at least two different materials.

Conditions for forming the HBL, ETL, and EIL of the electron transport region may be the same as those for the HIL described above.

When the electron transport region includes the HBL, the HBL may include at least one of BCP below and Bphen below. However, embodiments of the present disclosure are not limited thereto.

The thickness of the HBL may be from about 20 Å to about 1,000 Å, and in some embodiments, from about 30 Å to about 300 Å. When the thickness of the HBL is within these ranges, the HBL may have improved hole blocking ability without a substantial increase in driving voltage.

The ETL may further include at least one of Alq₃, Balq, TAZ, and NTAZ, in addition to BCP and Bphen described above.

In some embodiments, the ETL may include at least one of Compounds ET1 and ET2 represented below, but is not limited thereto.

A thickness of the ETL may be from about 100 Å to about 1,000 Å, and in some embodiments, from about 150 Å to about 500 Å. When the thickness of the ETL is within these ranges, the ETL may have satisfactory electron transporting ability without a substantial increase in driving voltage.

In some embodiments the ETL may further include a metal-containing material, in addition to the above-described materials.

The metal-containing material may include a lithium (Li) complex. Non-limiting examples of the Li complex are compound ET-D1 below (lithium quinolate (LiQ)), or compound ET-D2 below.

The electron transport region may include an EIL that may facilitate injection of electrons from the second electrode 19. The EIL may include at least one selected from LiF, NaCl, CsF, Li₂O, and BaO. The thickness of the EIL may be from about 1 Å to about 100 Å, and in some embodiments, from about 3 Å to about 90 Å. When the thickness of the EIL is within these ranges, the EIL may have satisfactory electron injection ability without a substantial increase in driving voltage.

The second electrode 19 is disposed on the organic layer 15. The second electrode 19 may be a cathode. A material for the second electrode 19 may be a metal, an alloy, or an electrically conductive compound that have a low work function, or a combination thereof. Non-limiting examples of the material for the second electrode 19 are lithium (Li), magnesium (Mg), aluminum (Al), aluminum (Al)-lithium (Li), calcium (Ca), magnesium (Mg)-indium (In), and magnesium (Mg)-silver (Ag), or the like. In some embodiments, to manufacture a top-emission light-emitting device, the second electrode 19 may be formed as a transmissive electrode from, for example, indium tin oxide (ITO) or indium zinc oxide (IZO).

Although the organic light-emitting device of FIG. 1 is described above, embodiments of the present disclosure are not limited thereto.

As used herein, a C₁-C₆₀ alkyl group refers to a linear or branched aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms. Non-limiting examples of the C₁-C₆₀ alkyl group a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an iso-amyl group, and a hexyl group. A C₁-C₆₀ alkylene group refers to a divalent group having the same structure as the C₁-C₆₀ alkyl.

As used herein, a C₁-C₆₀ alkoxy group refers to a monovalent group represented by —OA₁₀₁ (where A₁₀₁ is a C₁-C₆₀ alkyl group as described above. Non-limiting examples of the C₁-C₆₀ alkoxy group are a methoxy group, an ethoxy group, and an isopropyloxy group.

As used herein, a C₂-C₆₀ alkenyl group refers to a structure including at least one carbon double bond in the middle or at the terminal of the C₂-C₆₀ alkyl group. Non-limiting examples of the C₂-C₆₀ alkenyl group are an ethenyl group, a propenyl group, and a butenyl group. A C₂-C₆₀ alkylene group refers to a divalent group having the same structure as the C₂-C₆₀ alkenyl group.

As used herein, a C₂-C₆₀ alkynyl group refers to a structure including at least one carbon triple bond in the middle or at the terminal of the C₂-C₆₀ alkyl group. Non-limiting examples of the C₂-C₆₀ alkynyl group are an ethynyl group and a propynyl group. A C₂-C₆₀ alkynylene group used herein refers to a divalent group having the same structure as the C₂-C₆₀ alkynyl group.

As used herein, a C₃-C₁₀ cycloalkyl group refers to a monovalent, monocyclic hydrocarbon group having 3 to 10 carbon atoms. Non-limiting examples of the C₃-C₁₀ cycloalkyl group are a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. A C₃-C₁₀ cycloalkylene group refers to a divalent group having the same structure as the C₃-C₁₀ cycloalkyl group.

As used herein, a C₂-C₁₀ heterocycloalkyl group refers to a monovalent monocyclic group having 2 to 10 carbon atoms in which at least one hetero atom selected from N, O, P, and S is included as a ring-forming atom. Non-limiting examples of the C₃-C₁₀ heterocycloalkyl group are a tetrahydrofuranyl group and a tetrahydrothiophenyl group. A C₂-C₁₀ heterocycloalkylene group refers to a divalent group having the same structure as the C₂-C₁₀ heterocycloalkyl group.

As used herein, a C₃-C₁₀ cycloalkenyl group refers to a monovalent monocyclic group having 3 to 10 carbon atoms that includes at least one double bond in the ring but does not have aromaticity. Non-limiting examples of the C₃-C₁₀ cycloalkenyl group are a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. A C₃-C₁₀ cycloalkenylene group refers to a divalent group having the same structure as the C₃-C₁₀ cycloalkenyl group.

As used herein, a C₂-C₁₀ heterocydoalkenyl group used herein refers to a monovalent monocyclic group having 2 to 10 carbon atoms that includes at least one double bond in the ring and in which at least one hetero atom selected from N, O, P, and S is included as a ring-forming atom. Non-limiting examples of the C₂-C₁₀ heterocydoalkenyl group are a 2,3-dihydrofuranyl group and a 2,3-dihydrothiophenyl group. A C₂-C₁₀ heterocydoalkenylene group used herein refers to a divalent group having the same structure as the C₂-C₁₀ heterocycloalkenyl group.

As used herein, a C₆-C₆₀ aryl group refers to a monovalent, aromatic carbocydic aromatic group having 6 to 60 carbon atoms, and a C₆-C₆₀ arylene group refers to a divalent, aromatic carbocydic group having 6 to 60 carbon atoms. Non-limiting examples of the C₆-C₆₀ aryl group are a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene group include at least two rings, the rings may be fused to each other.

As used herein, a C₂-C₆₀ heteroaryl group refers to a monovalent, aromatic carbocydic aromatic group having 2 to 60 carbon atoms in which at least one heteroatom selected from N, O, P, and S is included as a ring-forming atom, and 2 to 60 carbon atoms. A C₂-C₆₀ heteroarylene group refers to a divalent, aromatic carbocydic group having 2 to 60 carbon atoms in which at least one hetero atom selected from N, O, P, and S is included as a ring-forming atom. Non-limiting examples of the C₂-C₆₀ heteroaryl group are a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group. When the C₂-C₆₀ heteroaryl and the C₂-C₆₀ heteroarylene include at least two rings, the rings may be fused to each other.

As used herein, a C₆-C₆₀ aryloxy group indicates —OA₁₀₂ (where A₁₀₂ is a C₆-C₆₀ aryl group as described above), and a C₆-C₆₀ arylthio group indicates —SA₁₀₃ (where A₁₀₃ is a C₆-C₆₀ aryl group as described above).

As used herein, a monovalent non-aromatic condensed polycydic group refers to a monovalent group having at least two rings condensed to each other, in which only carbon atoms (for example, 8 to 60 carbon atoms) are exclusively included as ring-forming atoms and the entire molecule is non-aromatic. A non-limiting example of the monovalent non-aromatic condensed polycydic group is a fluorenyl group. A divalent non-aromatic condensed polycydic group refers to a divalent group having the same structure as the monovalent non-aromatic condensed polycydic group.

As used herein, a monovalent non-aromatic condensed heteropolycydic group refers to a monovalent group having at least two rings condensed to each other, in which carbon atoms (for example, 2 to 60 carbon atoms) and a hetero atom selected from N, O, P, and S are as ring-forming atoms and the entire molecule is non-aromatic. A non-limiting example of the monovalent non-aromatic condensed heteropolycydic group is a carbazolyl group. A divalent non-aromatic condensed heteropolycydic group refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycydic group.

As used herein, at least one substituent of the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₂-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₂-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₂-C₆₀ heteroaryl group, the substituted monovalent non-aromatic condensed polycydic group, and the substituted monovalent non-aromatic condensed heteropolycydic group may be selected from

a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and C₁-C₆₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycydic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), and —B(Q₁₆)(Q₁₇),

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycydic group,

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycydic group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₁₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycydic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), and —B(Q₂₆)(Q₂₇), and

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), and —B(Q₃₆)(Q₃₇),

wherein Q₁ to Q₃, Q₁₁ to Q₁₇, Q₂₁ to Q₂₇, and Q₃₁ to Q₃₇ may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocydoalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycydic group.

In some embodiments, as used herein, at least one substituent of the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₂-C₁₀ heterocydoalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₂-C₁₀ heterocydoalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₂-C₆₀ heteroaryl group, the substituted monovalent non-aromatic condensed polycydic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from

a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₀ alkenyl group, a C₂-C₀ alkynyl group, and C₁-C₆₀ alkoxy group,

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a cyclopentyl group, a cydohexyl group, a cydoheptyl group, a cydopentenyl group, a cydoheptenyl group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), and —B(Q₁₆)(Q₁₇),

a cyclopentyl group, a cydohexyl group, a cydoheptyl group, a cydopentenyl group, a cydoheptenyl group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group,

a cyclopentyl group, a cyclohexyl group, a cydoheptyl group, a cyclopentenyl group, a cycloheptenyl group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a phenyl group, a naphthyl group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), and —B(Q₂₆)(Q₂₇), and

-   -   —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), and —B(Q₃₆)(Q₃₇),     -   wherein Q₁ to Q₃, Q₁₁ to Q₁₇, Q₂₁ to Q₂₇, and Q₃₁ to Q₃₇ may be         each independently selected from a hydrogen, a deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a cyclopentyl group, a         cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a         cycloheptenyl group, a phenyl group, a pentalenyl group, an         indenyl group, a naphthyl group, an azulenyl group, a heptalenyl         group, an indacenyl group, an acenaphthyl group, a fluorenyl         group, a spiro-fluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl         group, an anthracenyl group, a fluoranthenyl group, a         triphenylenyl group, a pyrenyl group, a chrysenyl group, a         naphthacenyl group, a picenyl group, a perylenyl group, a         pentaphenyl group, a hexacenyl group, a pentacenyl group, a         rubicenyl group, a coronenyl group, an ovalenyl group, a         pyrrolyl group, a thiophenyl group, a furanyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an isoindolyl group, an indolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a carbazolyl group, a         phenanthridinyl group, an acridinyl group, a phenanthrolinyl         group, a phenazinyl group, a benzoimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, and an         imidazopyrimidinyl group.

Hereinafter, the present inventive concept will be described in detail with reference to the following synthesis examples and other examples of compounds and organic light-emitting devices. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present inventive concept. In the following synthesis examples, the expression that “‘B’ instead of ‘A’ was used” means that the amounts of ‘B’ and ‘A’ were the same in equivalent amounts.

EXAMPLES Synthesis Example 1 Synthesis of Compound 52

A solution of n-BuLi in hexane (2.77 M, 0.14 mL, 0.4 mmol) was added to a solution of 3-trifluoromethyl pyrazole (0.4 mmol) in tetrahydrofuran (THF, 5 mL) in a 100-mL Schlenk flask at room temperature in an argon atmosphere. The resulting reaction product was stirred at room temperature for about 2 hours, and 50 mg (0.4 mmol) of diisopropylcarbodiimide was dropwise added thereto and stirred for about 2 hours. Then, a solution of Intermediate A (0.2 mmol) in THF (15 mL) was dropwise added thereto and stirred at about 80C for about 16 hours. The resulting reaction product was cooled down to room temperature, and then the solvent was removed under reduced pressure. The residue was dissolved in toluene, and the toluene was removed under reduced pressure, thereby completely removing THF from the residue. The resulting reaction product was dissolved again in toluene, filtered to remove lithium chloride, and washed with Et₂O to obtain Compound 52 (240 mg, Yield: 72%).

¹H NMR: 300 MHz, CDCl₃, rt: δ 8.30 (d, J=8.5 Hz, 2H,), 7.81 (m, 4H), 7.18 (t, 2H), 6.73 (s, 1H), 6.4 (s, 1H), 3.65-3.82 (m, 2H), 1.28 (d, 6H), 0.91 (d, 6H).

MS (MALDI-TOF) [m/e]: 828.20

Synthesis Example 2 Synthesis of Compound 19

Compound 19 (303 mg, Yield: 76%) was synthesized in the same manner as in Synthesis Example 1, except that Intermediate B instead of Intermediate A was used.

MS (MALDI-TOF) [m/e]: 998.2

Synthesis Example 3 Synthesis of Compound 2

Compound 2 (292 mg, Yield: 81%) was synthesized in the same manner as in Synthesis Example 1, except that 3,5-bis(trifluoromethyl)-pyrazole instead of 3-trifluoromethyl-pyrazole was used.

MS (MALDI-TOF) [m/e]: 904.1

Synthesis Example 4 Synthesis of Compound 50

Compound 50 (290 mg, Yield: 78%) was synthesized in the same manner as in Synthesis Example 1, except that pyrazole and Intermediate B instead of 3-trifluoromethyl pyrazole and Intermediate A, respectively, were used.

MS (MALDI-TOF) [m/e]: 930.0

Synthesis Example 5 Synthesis of Compound 1

Compound 1 (209 mg, Yield: 68%) was synthesized in the same manner as in Synthesis Example 1, except that pyrazole instead of 3-trifluoromethyl pyrazole was used.

MS (MALDI-TOF) [m/e]: 768.20

Synthesis Example 6 Synthesis of Compound 3

Compound 3 (268 mg, Yield: 82%) was synthesized in the same manner as in Synthesis Example 1, except that 4,5-dicyano-imidazole instead of 3-trifluoromethyl-pyrazole was used.

MS (MALDI-TOF) [m/e]: 818.10

Synthesis Example 7 Synthesis of Compound 5

Compound 5 (200 mg, Yield: 65%) was synthesized in the same manner as in Synthesis Example 1, except that 1,2,4-triazole instead of 3-trifluoromethyl-pyrazole was used.

MS (MALDI-TOF) [m/e]: 769.2

Synthesis Example 8 Synthesis of Compound 9

Compound 9 (298 mg, Yield: 80%) was synthesized in the same manner as in Synthesis Example 1, except that 1,2,4-triazole and Intermediate B instead of 3-trifluoromethyl-pyrazole and Intermediate A, respectively, were used.

MS (MALDI-TOF) [m/e]: 769.2

Synthesis Example 9 Synthesis of Compound 54

Compound 54 (223 mg, Yield: 62%) was synthesized in the same manner as in Synthesis Example 1, except that 5-methyl-tetrazole and Intermediate D instead of 3-trifluoromethyl-pyrazole and Intermediate A, respectively, were used.

MS (MALDI-TOF) [m/e]: 896.12

Synthesis Example 10 Synthesis of Compound 53

Compound 53 (220 mg, Yield: 58%) was synthesized in the same manner as in Synthesis Example 1, except that Intermediate D instead of Intermediate A was used.

¹H NMR: 300 MHz, CDCl₃, rt: δ 8.32 (d, J=8.45 Hz, 2H), 7.91 (m, 1H), 7.83 (d, 1H), 7.21 (d, 2H), 6.75 (s, 2H), 6.49 (s, 1H), 5.7 (s, 1H), 3.54-3.83 (m, 2H), 1.56 (d, 6H), 1.46 (s, 9H), 0.02 (d, 6H).

MS (MALDI-TOF) [m/e]: 948.34

Synthesis Example 11 Synthesis of Compound 51

Compound 51 (223 mg, Yield: 63%) was synthesized in the same manner as in Synthesis Example 1, except that Intermediate E instead of Intermediate A was used.

MS (MALDI-TOF) [m/e]: 884.20

Synthesis Example 12 Synthesis of Compound 56

Compound 56 (251 mg, Yield: 72%) was synthesized in the same manner as in Synthesis Example 1, except that Intermediate F instead of Intermediate A was used.

¹H NMR: 300 MHz, CDCl₃, rt: δ 8.99 (d, J=8.35 Hz, 2H), 7.97 (d, 2H), 6.79-6.94 (m, 4H), 6.70 (m, 2H), 6.55 (s, 1H), 6.07 (s, 1H), 4.25 (s, 3H), 3.31-3.36 (m, 2H), 2.07 (d, 6H), 1.16 (d, 6H).

MS (MALDI-TOF) [m/e]: 904.0

Synthesis Example 13 Synthesis of Compound 30

Compound 30 (194 mg, Yield: 52%) was synthesized in the same manner as in Synthesis Example 1, except that sodium dicyanoimide and Intermediate B instead of 3-trifluoromethyl-pyrazole and Intermediate A, respectively, were used.

MS (MALDI-TOF) [m/e]: 929.10

Evaluation Example 1: Evaluation of photoluminescence (PL) spectrum and photoluminescence quantum yield (PLQY)

Compound 52 was diluted in toluene to a concentration of 10 mM, and the photoluminescence (PL) of Compound 52 in the solution was measured using an ISC PC1 Spectrofluorometer equipped with a Xenon lamp. The same measurement was repeated for Compounds 19, 2, 50, 1, 3, 5, 9, 54, 53, 51, 56, and 30. PL spectra of Compounds 52, 19, 2, 50, 1, 3, 5, 9, 54, 53, 51, 56, and 30 are shown in FIGS. 2 to 14, respectively.

A solution of polymethylmethacrylate (PMMA) in CH₂Cl₂ was mixed with 8 weight % of Compound 52 to obtain a mixture. This mixture was coated on a quartz substrate by using a spin coater, thermally treated in a 80 C oven, and cooled down to room temperature to form a film. This film was used to evaluate photoluminescence quantum yield (PLQY) and color coordination of compound 52. The photoluminescence quantum yield in film and the color coordination in film of Compound 52 were evaluated using a Hamamatsu Photonics absolute PL quantum yield measurement system using PLQY measurement software (Hamamatsu Photonics, Ltd., Shizuoka, Japan), equipped with a Xenon light source, a monochromator, a photonic multichannel analyzer, and an integrating sphere. The same evaluation as above was repeated for Compounds 19, 2, 50, 1, 3, 5, 9, 54, 53, 51, 56, and 30 and Compounds A to D to obtain photoluminescence quantum yields and color purity data thereof, which are shown in Table 1.

TABLE 1 Compound No. PLQY (%) CIE_X CIE_Y 52 73 0.16 0.26 19 65 0.17 0.32  2 66 0.18 0.34 50 58 0.17 0.34  1 68 0.19 0.36  3 48 0.23 0.40  5 56 0.18 0.33  9 54 0.17 0.35 54 64 0.17 0.30 53 78 0.16 0.26 51 75 0.16 0.30 56 86 0.22 0.41 30 68 0.16 0.27 A 22 0.38 0.58 B 36 0.42 0.56 C 18 0.43 0.55 D 16 0.46 0.52

Referring to FIGS. 2 to 14 and Table 1, Compounds 52, 19, 2, 50, 1, 3, 5, 9, 54, 53, 51, 56, and 30 were found to have higher photoluminescence quantum yields compared to those of Compounds A, B, C, and D, and emit high-purity blue light.

As described above, according to the one or more of the above embodiments of the present inventive concept, an organometallic compound represented by Formula 1 may have improved electric characteristics and improved thermal stability, and thus an organic light-emitting device including the organometallic compound may have a low driving voltage, a high efficiency, a high luminance, and improved lifetime characteristics.

It should be understood that the exemplary embodiments described therein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. 

What is claimed is:
 1. An organometallic compound represented by Formula 1: Formula 1 M(L₁)_(n1)(L₂)_(n2) wherein, in Formula 1, L₁ is a ligand represented by Formula 2, and L₂ is a ligand represented by one of Formulae 3 to 5:

wherein, in Formulae 1 to 5, M is Ir, Pt, Os, Ti, Zr, Hf, Eu), Tb, or Tm; CY₁ and CY₂ are each independently a benzene, a naphthalene, a fluorene, a spiro-fluorene, an indene, a pyrrole, a thiophene, a furan, an imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isoxazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, an benzoxazole, an isobenzoxazole, a triazole, a tetrazole, an oxadiazole, a triazine, a dibenzofuran, or a dibenzothiophene, wherein CY₁ and CY₂ are optionally linked to each other via a single bond or a first linking group; Y₁ to Y₄ are each independently C or N; Y₁ and Y₂ are linked to each other via a single bond or a double bond, and Y₃ and Y₄ are linked to each other via a single bond or a double bond; X₁ is N or CR₁; X₂ is N or CR₂; X₃ is N or CR₃; X₄ is N or CR₄; X₁₁ is N or CR₁₁; X₁₂ is N or CR₁₂; X₁₃ is N or CR₁₃; X₁₄ is N or CR₁₄; X₁s is N or CR₁₅; X₁₆ is N or CR₁₆; Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₂-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, or —Si(Q₁)(Q₂)(Q₃), wherein R₂₁ and R₂₂ are optionally linked to each other via a single bond or a second linking group represented by Formula 7: *—(Z₃₂)_(b2)-*  Formula 7 wherein, in Formula 7, Z₃₂ is *—O—*, *—S—*, *—N(Q₅₁)-*, *—C(Q₅₂)(Q₅₃)—*, *—C(Q₅₄)=C(Q₅₅)-*′, or

b2 is an integer selected from 1 to 10, and when b2 is 2 or greater, groups Z₃₂ are identical to or different from each other; a1 and a2 are each independently an integer selected from 0 to 5; n1 and n2 are each independently 1 or 2; * and *′ each indicates a binding site to M in Formula 1; when the ligand of Formula 2 is represented by Formula 2A, a2 in Formula 2A is 2, and Z₂ in Formula 2A is —F; at least one of X₁₁ to X₁₆ in Formula 4 is N; the following conditions regarding R₂₁ and R₂₂ in Formula 5 are excluded: i) where R₂₁ and R₂₂ are both phenyl groups, ii) where R₂₁ and R₂₂ are both phenyl groups substituted with a tert-butyl group, iii) where R₂₁ and R₂₂ are both ethyl groups, iv) where R₂₁ and R₂₂ are both propyl groups, v) where R₂₁ and R₂₂ are both butyl groups, and vi) where R₂₁ and R₂₂ are both —Si(CH₃)3; at least one substituent of the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₂-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₂- C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₂-C₆₀ heteroaryl group, the substituted monovalent non-aromatic condensed polycydic group, and the substituted monovalent non-aromatic condensed heteropolycydic group is a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₀ alkenyl group, a C₂-C₀ alkynyl group, or a C₁-C₆₀ alkoxy group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocydoalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocydoalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycydic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), and —B(Q₁₆)(Q₁₇), a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocydoalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycydic group, or a monovalent non-aromatic condensed heteropolycydic group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocydoalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycydic group, or a monovalent non-aromatic condensed heteropolycydic group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycydic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅), and —B(Q₂₆)(Q₂₇), or —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Qs₃₄)(Q₃₅), or —B(Q₃₆)(Q₃₇); wherein Q₁ to Q₃, Q₁₁ to Q₁₇, Q₂₁ to Q₂₇, and Q₃₁ to Q₃₇ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₂-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycydic group, or a monovalent non-aromatic condensed heteropolycyclic group:


2. The organometallic compound of claim 1, wherein the organometallic compound of Formula 1 is represented by Formula 1A, 1B, or 1C:

wherein, in Formulae 1A to 1C, M, CY₁, CY₂, Y₁ to Y₄, X₁ to X₄, X₁₁ to X₁₆, Z₁ to Z₄, R₂₁, R₂₂, n1, and n2 are the same as those defined in claim
 1. 3. The organometallic compound of claim 1, wherein M is Ir or Pt.
 4. The organometallic compound of claim 1, wherein CY₁ and CY₂ are each independently a benzene, a naphthalene, a fluorene, a thiophene, a furan, an imidazole, a pyrazole, a pyridine, a pyrimidine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, a triazole, a tetrazole, a triazine, a dibenzofuran, or a dibenzothiophene.
 5. The organometallic compound of claim 1, wherein CY₁ is a pyridine or an imidazole, and CY₂ is a benzene, a pyridine, or a dibenzofuran.
 6. The organometallic compound of claim 1, wherein CY₁ and CY₂ are linked to each other via a single bond or the first linking group, and the first linking group is a linking group represented by Formula 6: *—(Z₃₁)_(b1)-*  Formula 6 wherein, in Formula 6, Z₃₁ is selected from *—O—*′, *—S—*′, *—N(Q₄₁)-*′, *—C(Q₄₂)(Q₄₃)-*, *—C(Q₄₄)=C(Q₄₅)-*′, and,

wherein Q₄₁ to Q₄₉ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinyl group, or a phenyl group, a naphthyl group, a pyridinyl group, or a pyrimidinyl group.
 7. The organometallic compound of claim 1, wherein L₁ in Formula 1 is selected from groups represented by Formulae 2-1 to 2-90:

wherein, in Formulae 2-1 to 2-90, Z₁ and Z₂ are the same as those defined in claim 1; Z_(1a) and Z_(1b) are the same or different and each has the same definition as Z₁; Z_(2a), Z_(2b) and Z_(2c) are the same or different and each has the same definition as Z₂; a12 is 1 or 2; a13 is an integer selected from 1 to 3; a14 is an integer selected from 1 to 4; and * and *′ each indicates a binding site to M.
 8. The organometallic compound of claim 1, wherein L₁ in Formula 1 is selected from groups represented by Formulae 2-1A, 2-2a, 2-70A, and 2-87A:

wherein, in Formulae 2-1A, 2-2A, 2-70A, and 2-87A, Z₁ and Z₂ are the same as those defined in claim 1, Z_(2a), Z_(2b), and Z_(2c) are the same or different and each has the same definition as Z₂, and * and *′ each indicates a binding site to M.
 9. The organometallic compound of claim 1, wherein Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinyl group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, a ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, a oxazolyl group, an isooxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzooxazolyl group, an isobenzooxazolyl group, a triazolyl group, a tetrazolyl group, a oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a thiadiazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, an ovalenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthridinyl group, an acridinyl group, a phenanthrolinyl group, a phenazinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, a fluorenyl group, a chrysenyl group, a carbazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, a quinazolinyl group, or a quinoxalinyl group.
 10. The organometallic compound of claim 1, wherein Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Q₅₉ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or a triazinyl group.
 11. The organometallic compound of claim 1, wherein Z₁ to Z₄, R₁ to R₄, R₁₁ to R₁₆, R₂₁, R₂₂, and Q₅₁ to Qs₅₉ are each independently a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, a isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group, or —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ are each independently a hydrogen, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or a triazinyl group.
 12. The organometallic compound of claim 1, wherein at least one of X₁ to X₄ in Formula 3 is N.
 13. The organometallic compound of claim 1, wherein L₂ in Formula 1 is represented by one of Formulae 3-1 to 3-4 and Formulae 4-1 to 4-4:

wherein, in Formulae 3-1 to 3-4, and Formulae 4-1 to 4-4, Z₃, Z₄, R₁ to R₄, and R₁₁ to R₁₆ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, or a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; and * and *′ each indicates a binding site to M.
 14. The organometallic compound of claim 1, wherein R₂₁ and R₂₂ in Formula 5 are each independently a cyano group or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, or —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ are each independently a hydrogen, a phenyl group, or a naphthyl group; and at least one of R₂₁ and R₂₂ in Formula 5 is a cyano group or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, or a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group.
 15. The organometallic compound of claim 1, wherein R₂₁ and R₂₂ in Formula 5 are each independently a cyano group or a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, or —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ are each independently a hydrogen, a phenyl group, or a naphthyl group; and at least one of R₂₁ and R₂₂ in Formula 5 is a cyano group or a C₁-C₂₀ alkoxy group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, or a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl group.
 16. The organometallic compound of claim 1, wherein L₂ in Formula 1 is represented by Formula 5A or 5B:

wherein, in Formulae 5A and 5B, Z₃, Z₄, Z₃₂, and b2 are the same as those defined in claim 1; X₃₁ is N or CR₃₁; X₃₂ is N or CR₃₂; X₃₃ is N or CR₃₃; X₃₄ is N or CR₃₄; X₃₅ is N or CR₃₅; X₃₆ is N or CR₃₆; X₃₇ is N or CR₃₇; X₃₈ is N or CR₃₈; at least one of X₃₁ to X₃₈ is N; and R₃₁ to R₃₈ are the same or different and each has the same definition as for R₁.
 17. The organometallic compound of claim 16, wherein R₃₁ to R₃₈ in Formulae 5A and 5B are each independently a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group.
 18. The organometallic compound of claim 1, wherein L₂ in Formula 1 is selected from groups represented by Formulae 5-1 to 5-25:

wherein, in Formulae 5-1 to 5-25, Z₃, Z₄, R₃₁ to R₃₈, and Q₅₂ to Q₅₅ are each independently a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, or a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, or a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzoimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; d1 is an integer selected from 1 to 4; d2 is an integer selected from 1 to 5; d3 is an integer selected from 1 to 3; d4 is 1 or 2; and d5 is an integer selected from 1 to
 7. 19. The organometallic compound of claim 1, wherein CY₁ is a pyridine or an imidazole; CY₂ is a benzene, a pyridine, or a dibenzofuran; Z₁ and Z₂ are each independently a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of-F, a cyano group, and a nitro group; and L₂ in Formula 1 is represented by one of Formulae 3-1 to 3-4, Formulae 4-1 to 4-4, and Formulae 5-1 to 5-25:

wherein, in Formulae 3-1 to 3-4, Formulae 4-1 to 4-4, and Formulae 5-1 to 5-25, Z₃, Z₄, R₁ to R₄, R₁₁ to R₁₆, R₃₁ to R₃₈, and Q₅₂ to Q₅₅ are each independently a hydrogen, —F, a cyano group, a nitro group, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, or a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, a n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, a n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a phenyl group, or a naphthyl group, each substituted with at least one of —F, a cyano group, and a nitro group; d1 is an integer selected from 1 to 4; d2 is an integer selected from 1 to 5; d3 is an integer selected from 1 to 3; d4 is 1 or 2; d5 is an integer selected from 1 to 7; and * and *′ each indicates a binding site to M in Formula
 1. 20. The organometallic compound of claim 1, wherein the organometallic compound of Formula 1 is one of Compounds 1 to 56:


21. An organic light-emitting device comprising: a first electrode; a second electrode; and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer comprises an emission layer and at least one of the organometallic compounds of claim
 1. 22. The organic light-emitting device of claim 21, wherein the first electrode is an anode, the second electrode is a cathode, and the organic layer comprises i) a hole transport region disposed between the first electrode and the emission layer and comprising at least one of a hole injection layer, a hole transport layer, and an electron blocking layer, and ii) an electron transport region disposed between the emission layer and the second electrode and comprising at least one of a hole blocking layer, an electron transport layer, and an electron injection layer.
 23. The organic light-emitting device of claim 21, wherein the emission layer comprises the at least one of the organometallic compounds.
 24. The organic light-emitting device of claim 23, wherein the emission layer further comprises a host. 